The present invention relates to a coating composition for lenses, a method of producing the same, and a coated lens.
There is a present need to manufacture plastic articles that are scratch resistant and have an aesthetic appearance. Scratch resistance is typically provided by applying a coating composition to a surface of the plastic article, followed by curing the coating composition.
Curing catalysts are typically used in the coating composition to facilitate the curing process. For example, Japanese Patent Publication No. 33868/1986 discloses amine compounds, and Japanese Patent Publication No. 11727/1985 discloses aluminum or iron acetylacetonates curing catalysts.
However, the acetylacetonates can be problematic, in that they tend to reduce the shelf life of coating compositions. Because coating compositions can be expensive, an improvement of their storage stability, that is, an increase of their shelf life is desired. Also, coating compositions with improved storage stability are desired because the quality of the coated lens can be related to the shelf life of the coating composition. Coating compositions with a relatively long shelf life tend provide a relatively strong adhesive bond between the lens and the cured coating. The present invention overcomes prior coating compositions by providing a coating composition for lenses with a relatively long shelf life.
One embodiment of this invention is a method for producing a coating composition for a lens comprising providing a mixture comprising metal oxide colloid particles and an organosilicon compound; and adding an acetylacetonate metal salt and an aliphatic amine to the mixture. The organosilicon compound could be selected from compounds of the general formula (I):
(R1)a(R3)bSi(OR2)4xe2x88x92(a+b)xe2x80x83xe2x80x83(I) 
wherein R1 and R3 are independently a hydrocarbon group having from 1 to 10 carbon atoms and optionally having a functional group; R2 is selected from an alkyl group having from 1 to 8 carbon atoms, an aryl group having from 6 to 10 carbon atoms, an alkyl group having from 7 to 10 carbon atoms that includes an aryl group, an acyl group having from 1 to 8 carbon atoms or the combinations thereof; and a and b are 0 or 1; and (OR2)""s may be the same or different, or compounds of the general formula (II): 
wherein R4 and R5 are a hydrocarbon group having from 1 to 5 carbon atoms and optionally having a functional group; X1 and X2 independently comprise a group selected from an alkyl group having from 1 to 4 carbon atoms, an acyl group having from 1 to 4 carbon atoms, the hydrolyzate products thereof, or the combinations thereof; Y represents a hydrocarbon group having from 1 to 20 carbon atoms; and x and y is 0 or 1.
In a preferred embodiment, the coating composition comprises between 1 and 500 parts by weight of the metal oxide colloid particles, and between 0.001 and 10 parts by weight of the aliphatic amine, relative to 100 parts by weight of the organosilicon compound. In another preferred embodiment, the metal oxide colloid particles are selected from aluminum oxide, iron oxide, tin oxide, zirconium oxide, silicon oxide, titanium oxide, tungsten oxide, antimony oxide, or their composite oxides. In yet another preferred embodiment, the aliphatic amine and the acetylacetonate metal salt are added to the mixture after a portion of the metal particles and the organosilicon compound react.
Another embodiment of this invention is a coating composition for lenses produced by the process comprising providing a mixture comprising metal oxide colloid particles and an organosilicon compound; and adding an acetylacetonate metal salt and an aliphatic amine to the mixture.
Another embodiment of this invention is a method for producing a coated lens, comprising producing a coating composition, applying the coating composition to a surface of a lens, and curing the coating composition; wherein the coating composition is produced by providing a mixture comprising metal oxide colloid particles and an organosilicon compound, and adding an acetylacetonate metal salt and an aliphatic amine to the mixture.
Yet another embodiment of this invention is a coated lens comprising a lens; and a cured coating disposed on a surface of the lens, wherein the cured coating results from curing a coating composition applied to the lens, the coating composition produced by the process comprising providing a mixture comprising metal oxide colloid particles and an organosilicon compound; and adding an acetylacetonate metal salt and an aliphatic amine to the mixture.
Still another embodiment is a coating composition for lenses comprising a mixture, the mixture comprising metal oxide colloid particles, an organosilicon compound, an acetylacetonate metal salt and an aliphatic amine, or a product of a reaction of the mixture.
The invention is directed to a coating composition for lenses. The coating composition with a relatively high shelf life comprises adding an acetylacetonate metal salt that serves as a curing agent and an aliphatic amine to a mixture comprising metal oxide colloid particles and an organosilicon compound.
The metal oxide colloid particles are not specifically limited. Examples of the metal oxide colloid particles are particles, desirably fine particles, of single metal oxides such as aluminum oxide, titanium oxide, antimony oxide, tin oxide, zirconium oxide, silicon oxide, cerium oxide, iron oxide, etc., disclosed in Japanese Patent Laid-Open No. 113760/1996. Japanese Patent Laid-Open No. 217230/1991 discloses titanium oxide, cerium oxide and silicon oxide. Particles of metal composite oxides, for example, particles of tin oxide-zirconium oxide-tungsten oxide disclosed in Japanese Patent Laid-Open No. 25603/1994, and tin oxide-tungsten oxide disclosed in, titanium oxide-zirconium oxide-tin oxide disclosed in Japanese Patent Laid-Open No. 306258/1998, titanium oxide-zirconium oxide-silicon oxide, and those of a composite, stannic oxide-zirconium oxide-tungsten oxide disclosed in Japanese Patent Laid-Open No. 21901/1997, etc. The mean particle size of the metal oxide colloid particles may fall generally between 1 and 500 nm. One or a combination of different metal oxide colloid particles may be used.
The amount of metal oxide particles in the composition can be between 1 and 500 parts by weight, preferably between 10 and 200 parts by weight, and more preferably between 50 and 150 parts by weight, relative to 100 parts by weight of the organosilicon compound therein.
The organosilicon compound is selected from compounds of the general formula (I):
(R1)a(R3)bSi(OR2)4xe2x88x92(a+b)xe2x80x83xe2x80x83(I) 
wherein R1 and R3 are independently a hydrocarbon group selected from an alkyl group having from 1 to 10 carbon atoms, an alkenyl group having from 2 to 10 carbon atoms, an aryl group having from 6 to 10 carbon atoms, an alkyl group having from 7 to 10 carbon atoms that includes an aryl group, or an acyl group having from 1 to 8 carbon atoms; R2 is selected from an alkyl group having from 1 to 8 carbon atoms, an aryl group having from 6 to 10 carbon atoms, a alkyl group having from 7 to 10 carbon atoms including an aryl group, or an acyl group having from 1 to 8 carbon atoms; and a and b are 0 or 1; and (OR2)""s may be the same or different, or compounds of the general formula (II): 
wherein R4 and R5 are a hydrocarbon group having from 1 to 5 carbon atoms; X1 and X2 independently comprise a group selected from an alkyl group having from 1 to 4 carbon atoms, an acyl group having from 1 to 4 carbon atoms, the hydrolyzate products thereof, or the mixtures thereof; Y represents a hydrocarbon group having from 1 to 20 carbon atoms; and x and y is 0 or 1.
In formula (I), if R1 and R3 are alkyl and/or alkenyl groups, these groups can independently be linear, branched or cyclic. Examples of the alkyl group having from 1 to 10 carbon atoms are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, octyl, cyclopentyl, cyclohexyl, etc. Examples of the alkenyl group include vinyl, allyl, butenyl, hexenyl, octenyl, etc. Examples of the aryl group include phenyl, tolyl, xylyl, naphthyl, etc. Examples of the alkyl group having an aryl group include benzyl, phenethyl, naphthylmethyl, etc. All of these stated hydrocarbon groups may have an attached functional group moiety. The functional group includes a halogen atom, a glycidoxy group, an epoxy group, an amino group, a cyano group, a mercapto group, a (meth)acryloxy group, etc. Examples of the hydrocarbon group having from 1 to 10 carbon atoms and having such a functional group are a glycidoxymethyl group, an xcex1-glycidoxyethyl group, a xcex2-glycidoxyethyl group, an xcex1-glycidoxypropyl group, a xcex2-glycidoxypropyl group, a xcex3-glycidoxypropyl group, an xcex1-glycidoxybutyl group, a xcex2-glycidoxybutyl group, a xcex3-glycidoxybutyl group, a xcex4-glycidoxybutyl group, a (3,4-epoxycyclohexyl)methyl group, a xcex2-(3,4-epoxycyclohexyl)ethyl group, a xcex3-(3,4-epoxycyclohexyl)propyl group, a xcex4-(3,4-epoxycyclohexyl)butyl group, a chloromethyl group, a xcex3-chloropropyl group, a 3,3,3-trifluoropropyl group, a xcex3-methacryloxypropyl group, a xcex3-acryloxypropyl group, a xcex3-mercaptopropyl group, a xcex2-cyanoethyl group, an N-(xcex2-aminoethyl)-xcex3-aminopropyl group, a xcex3-aminopropyl group, etc.
The alkyl group having from 1 to 8 carbon atoms for R2 may be linear, branched or cyclic. Examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, cyclopentyl, cyclohexyl, etc. Examples of the aryl group for R2 include phenyl, tolyl, xylyl, etc.; and examples of the alkyl group having an aryl moiety for R2 include benzyl, phenethyl, etc. The acyl group for R2 includes an acetyl group, etc. The subscripts a and b can be 0 or 1; and the (OR2)""s may be the same or different.
Examples of the compound of the general formula (I) are methyl silicate, ethyl silicate, n-propyl silicate, isopropyl silicate, n-butyl silicate, sec-butyl silicate, tert-butyl silicate, tetraacetoxysilane, methyltrimethoxysilane, methyltripropoxysilane, methyltriacetoxysilane, methyltributoxysilane, methyltriamyloxysilane, methyltriphenoxysilane, methyltribenzyloxysilane, methyltriphenethyloxysilane, glycidoxymethyltriethoxysilane, glycidoxymethyltrimethoxysilane, xcex1-glycidoxyethyltrimethoxysilane, xcex1-glycidoxyethyltriethoxysilane, xcex2-glycidoxyethyltriethoxysilane, xcex1-glycidoxypropyltrimethoxysilane, xcex1-glycidoxypropyltriethoxysilane, xcex2-glycidoxypropyltrimethoxysilane, xcex2-glycidoxypropyltriethoxysilane, xcex3-glycidoxypropyltrimethoxysilane, xcex3-glycidoxypropyltriethoxysilane, xcex3-glycidoxypropyltripropoxysilane, xcex3-glycidoxypropyltriphenoxysilane, xcex1-glycidoxybutyltrimethoxysilane, xcex1-glycidoxybutyltriethoxysilane, xcex2-glycidoxybutyltrimethoxysilane, xcex2-glycidoxybutyltriethoxysilane, xcex3-glycidoxybutyltrimethoxysilane, xcex3-glycidoxybutyltriethoxysilane, xcex4-glycidoxybutyltrimethoxysilane, xcex4-glycidoxybutyltriethoxysilane, (3,4-epoxycyclohexyl)methyltriethoxysilane, (3,4-epoxycyclohexyl)methytrimethoxysilane, xcex2-(3,4-epoxy cyclohexyl)ethyltriethoxysilane, xcex2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, xcex2-(3,4-epoxycyclohexyl)ethyltripropoxysilane, xcex2-(3,4-epoxycyclohexyl)ethyltributoxysilane, xcex2-(3,4-epoxycyclohexyl)ethyltriphenoxysilane, xcex3-(3,4-epoxycyclohexyl)propyltrimethoxysilane, xcex3-(3,4-epoxycyclohexyl)propyltriethoxysilane, xcex4-(3,4-epoxycyclohexyl)butyltrimethoxysilane, xcex4-(3,4-epoxycyclohexyl)butyltriethoxysilane, glycidoxymethyheth oyldimethoxysilane, glycidoxymethylmethyldiethoxysilane, xcex1-gycidoxyethyhnethyldimethoxysilane, xcex1-glycidoxyethylmethyldiethoxysilane, xcex2-glycidoxyethylmethyldimethoxysilane, xcex2-glycidoxyethylmethyldiethoxysilane, xcex1-glycidoxypropylmethyldimethoxysilane, xcex1-glycidoxypropylmethyldiethoxysilane, xcex2-glycidoxypropylmethyldimethoxysilane, xcex1-glycidoxypropylmethyldiethoxysilane, xcex3-glycidoxypropylmethyldimethoxysilane, xcex3-glycidoxypropylmethyldiethoxysilane, xcex3-glycidoxypropylmethyldipropoxysilane, xcex3-glycidoxypropylmethyldibutoxysilane, xcex3-glycidoxypropylmethyldiphenoxysilane, xcex3-glycidoxypropylethyldimethoxysilane, xcex3-glycidoxypropylethyldiethoxysilane, xcex3-glycidoxypropylvinyldimethoxysilane, xcex3-glycidoxypropylvinyldiethoxysilane, xcex3-glycidoxypropylphenyldimethoxysilane, xcex3-glycidoxypropylphenyldiethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, vinyltriacetoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriacetoxysilane, xcex3-chloropropyltrimethoxysilane, xcex3-chloropropyltriacetoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, xcex3-methacryloxypropyltrimethoxysilane, xcex3-mercaptopropyltrimethoxysilane, xcex3-mercaptopropyltriethoxysilane, xcex2-cyanoethyltriethoxysilane, chloromethyltrimethoxysilane, chloromethyltriethoxysilane, N-(xcex2-aminoethyl)-xcex3-aminopropyltrimethoxysilane, N-(xcex2-aminoethyl)-xcex3-aminopropylmethyldimethoxysilane, xcex3-aminopropylmethyldimethoxysilane, N-(xcex2-aminoethyl)-xcex3-aminopropylmethyldiethoxysilane, dimethyldimethoxysilane, phenylmethyldimethoxysilane, dimethyldiethoxysilane, phenylmethyldiethoxysilane, xcex3-chloropropylmethyldiethoxysilane, xcex3-chloropropylmethyldimethoxysilane, dimethyldiacetoxysilane, xcex3-methacryloxypropylmethyldimethoxysilane, xcex3-methacryloxypropylmethyldiethoxysilane, xcex3-mercaptopropylmethyldimethoxysilane, xcex3-mercaptopropylmethyldiethoxysilane, methylvinyldimethoxysilane, methylvinyldiethoxysilane, etc.
In the general formula (II), the alkyl group having from 1 to 4 carbon atoms for X1 and X2 includes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, etc.; and the acyl group having from 1 to 4 carbon atoms is preferably an acetyl group. These X1 and X2 may be the same or different. The hydrocarbon group for R4 and R5 includes an alkyl group having from 1 to 5 carbon atoms, and an alkenyl group having from 2 to 5 carbon atoms. These may be linear, branched or cyclic. Examples of the alkyl group are methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, etc. Examples of the alkenyl group are vinyl, allyl, butenyl, etc. These hydrocarbon groups may have an attached functional group moiety. For the functional group and the functional group-having hydrocarbon group, referred to are the same as those mentioned above for R1 and R3 in the general formula (I). These R4 and R5 may be the same or different. Y is a hydrocarbon group having from 1 to 20 carbon atoms Preferred are an alkylene group or an alkylidene group, including, for example, methylene, ethylene, propylene, butylene, pentylene, hexylene, octylene, ethylidene, propylidene, etc. The subscripts x and y can be 0 or 1; the (OX1) groups can be the same or different, and the (OX2) groups can be the same or different.
Examples of the compound of the general formula (II) are methylenebis(methyldimethoxysilane), ethylenebis(ethyldimethoxysilane), propylenebis(ethyldiethoxysilane), butylenebis(methyldiethoxysilane), etc.
In the coating composition of the invention, the organosilicon compound can be selected from the compounds of the general formula (I) and (II), any combination thereof or their hydrolyzate products. The hydrolyzates may be prepared by adding an aqueous basic solution such as an aqueous solution of sodium hydroxide, ammonia or the like, or an aqueous acidic solution such as an aqueous solution of hydrochloric acid, acetic acid, citric acid or the like to a compound of the general formula (I) or (II).
In the coating composition of the invention, the acetylacetonate metal salt serves as a curing agent. The acetylacetonate metal salt can be a metal complex with the general formula:
M1(CH3COCHCOCH3)n1(OR6)n2 
wherein M1 represents Zn(II), Ti(IV), Co(II), Fe(II), Cr(III), Mn(II), V(III), V(IV), Ca(II), Co(III), Cu(II), Mg(II), or Ni(II); R6 represents a hydrocarbon group having from 1 to 8 carbon atoms; n1+n2 is a number corresponding to the valence of M, n. is 2, 3 or 4, and n2 is 0, 1 or 2. R6 is a hydrocarbon group having from 1 to 8 carbon atoms, the substituents in general formula (I).
Preferably, the amount of the acetylacetonate metal salt in the coating composition is between 0.001 and 50 parts by weight, and more preferably between 0.1 and 10 parts by weight, relative to 100 parts by weight of the organosilicon compound therein. If the amount of the metal salt is smaller than 0.001 part by weight, the curing of the coating composition can be insufficient. If the amount of the metal salt is larger than 50 parts by weight, the cured film can exhibit poor physical properties.
The use of an aliphatic amine (is believed to increase the shelf life of the coating composition. Although it is known that aliphatic amines can serve as a curing agent for coating compositions, it is not known that they can also serve to increase the shelf life of coating compositions. The aliphatic amine includes, for example, those of the following formula:
NR7R8R9 
wherein N is a nitrogen atom; and R7, R8 and R9 are independently a hydrogen atom or an aliphatic group. Examples of some aliphatic amines it includes allylamine, diallylamine, i-propylamine, propylamine, butylamine, i-butylamine, t-butylamine, sec-butylamine, methylamine, ethylamine, diethylamine, dibutylamine, diisobutylamine, diisopropylamine, tri-n-octylamine, ethoxypropylamine, methoxypropylamine, etc.
Preferably, the amount of the aliphatic amine in the composition is between 0.001 and 10 parts by weight, more preferably, between 0.01 and 10 parts by weight, relative to 100 parts by weight of the organosilicon compound therein. If the amount of aliphatic amine in the composition is less than 0.001 part by weight, the storage stability of the coating composition exhibits little or no improvement. If the amount of aliphatic amine is greater than 10 parts by weight, the cured coating can exhibit poor physical properties.
The coating composition of the invention is prepared by providing a mixture comprising metal oxide colloid particles and one or more organosilicon compounds. The acetylacetonate metal salt and the aliphatic amine are then added to the mixture. It is especially preferred, after the metal oxide particles and the organosilicon compound have been mixed and hydrolyzed, the acetylacetonate metal salt and the aliphatic amine are added to the mixture. The method of making the coating composition provides a coating composition with a relatively high shelf life. Also, the invention provides a coating with a relatively strong adhesive bond to the lens, and the coated lenses are scratch resistant.
If desired, various organic solvents and surfactants may be added to the coating composition to improve the wettability of the composition applied to the lens and to improve the surface texture of the cured coating. Typically, a surface with a smooth texture is desired. Also, UV absorbents, antioxidants, light stabilizers and anti-aging agents can also be added to the coating composition. Desirably, these additive components should not have any negative influence on the properties of the coating composition or on the properties of the coating.
The lens of the invention includes, lenses made of plastics for example, methyl methacrylate homopolymers, copolymers of methyl methacrylate with at least one other monomers, diethylene glycol bisallylcarbonate homopolymers, copolymers of diethylene glycol bisallylcarbonate with at least one other monomer, sulfur-containing copolymers, halogen-containing copolymers, polycarbonates, polystyrenes, polyvinyl chlorides, unsaturated polyesters, polyethylene terephthalates, polyurethanes, polythiourethanes, etc.
The coated lens of the invention is produced by applying a coating composition to a surface of a lens, followed by curing the coating composition to form a cured coating thereon. The cured coating adheres to the lens without the lens being subjected to a physical or chemical pre-treatment. However, that is not to say that the lens to be coated may not be previously subjected to any conventional pretreatment to improve the film adhesive strength. Chemical treatments that can be used to pre-treat the lens include contacting with any of acids, alkalis and various organic solvents, washing with various detergents, or treating with primer resins. Physical pre-treatments that can be used include physical treatment with plasma, UV rays or the like, or sand blasting. The chemical and/or physical pre-treatments enhance the adhesive bond between the lens and the cured coating.
For applying the coating composition onto the surface of a lens any method known to those skilled in the art can be used, including but not limited to, dip coating, spin coating, or spraying. It is preferred, that the coating composition be applied by dip coating or spin coating. The applied coating composition is then cured by drying in hot air or by exposing the coated lens to a light source. Preferably, the applied coating is cured in hot air at 70xc2x0 C. to about 200xc2x0 C., and more preferably from about 90xc2x0 C. to about 150xc2x0 C. One of the light sources can include a light source that generates far-infrared radiation.
The invention is described in more detail with reference to the following Examples. The described examples are not intended to restrict the scope of the invention.